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4" Apochromatic Hyper Shootout

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#401 Fomalhaut

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Posted 10 September 2008 - 08:13 AM

I've read your interesting review which you mention long ago. Spherochromatism which is a major inherent problem in short-focus-lenses seems to be reduced by the Extender-Q.
So, how would you, Dave, approximately rate the FSQ-106's visual performance, compared to TSA, FCT and/or FS, when used WITH the Extender-Q?
Chris

 

#402 Dave Novoselsky

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Posted 10 September 2008 - 08:25 AM

The original FSQ with the Extender was neck and neck with the then current 102, although, as Dan points out, individual examples of both varied. (I had one FSQ, and another early member had another, the performing slightly differently and one better than the other, ditto on the several FS 102s then quit common.) And, at the time, one of the guys had a spectacular FC 100 that would outperform all of the FS102s and the FSQs we had available. The 'champ' of our informal 4" challenge was my hand selected by Tom Back TMB 100 f/8.

Still working in the new Q and new Extender ED so can't answer your direct question. Dave
 

#403 KaStern

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Posted 10 September 2008 - 08:36 AM

Hello Daniel,

If that is your website, then I am very impressed.



it is the website of my friend Sven Wienstein.
Only the barlow/eyepiece comparison was made by both him and me,
using his 12" and 8" f/4 Newts, my 8"f/6 ATM Dobsonian and the
102/800mm TMB supplied by APM telescopes for this eyepiece comparison.
I remember that most of the comparison was done with the TMB and my 8"f/6.
Fortunately we had some nights with very stable wheather conditions.

Thank your your further information, I allways like to read them :waytogo:

Regards, Karsten
 

#404 Astronomics

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Posted 10 September 2008 - 12:37 PM

You will see my fingerprints all over this thread. I made the edits to keep the thread on topic. Let's keep this train a rollin. If you have any questions, feel free to PM me.
 

#405 Dave Novoselsky

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Posted 10 September 2008 - 12:54 PM

Hello Daniel,

could you ever compare a 102mm Vixen Fluorite (fluorite crystal, like
the Takahashi FS, Zeiss APQ and some other scopes) to a 102mm Takahashi FS?
Some years ago I could observe with a 4" Vixen and was very pleased with
it`s performance. Concerning the 102/800mm TMB I can tell that Sven Wienstein
and me used one of them for our eyepiece and barlow comparisons:

http://www.svenwiens...arlow-test.html

It was unspectacular in a very positive way. No colour issues at all
and contrasty views. I would really like to compare it to a Takahashi TSA.

Regards, Karsten


I believe the Vixen and Tak FC series of flourite doublets both had the outer element flourite. The later FS series switched and put the flourite on the inner side of the doublet lens cell. As to which arrangement was better, there was a fairly strong dichotomy in the Tak community when the switch was made. Some thought the change resulted in a loss of 'sharpness' while others thought that the switch enhanced contrast and favored the FS. I, for one, thought it was individual scope dependent and will let you go to the Uncensored Tak group where the debate continues from time to time even today.

I have a 90FL Vixen and 100FL badged as an Orion but built and marked as a Vixen. I have an FC 76 and an FC 100 (currently in transit) and these four scopes all seem to perform in a very similar fashion. Compared to 'modern' scopes in the the 3.5 to 4 aperture range, they are right up at in the top bracket but haven't done a recent test to do any ranking against the rest of my APO 'fleet.'

Tak also built flourite triplets, and I have an FCT 100 and a 150. My only other flourite triplet is a Zeiss 100/640 APQ. Those too also are supreb, the first and last being no doubt candidates along with the Vixen and the Tak doublets for further comparisons. Depends on whether time, location (Dan is out in Arnolt land and I live in Cheeseville) and other issues arise, but if Dan is game, I can try shipping him a scope or two from time to time to review. Dave
 

#406 Dave Novoselsky

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Posted 10 September 2008 - 12:57 PM

I've read your interesting review which you mention long ago. Spherochromatism which is a major inherent problem in short-focus-lenses seems to be reduced by the Extender-Q.
So, how would you, Dave, approximately rate the FSQ-106's visual performance, compared to TSA, FCT and/or FS, when used WITH the Extender-Q?
Chris


I just had a thought. I wonder how the Extender ED or original Extender Q would work with the short fl Zeiss 100/640? Markus, you work with both Tak and Zeiss optics, do you see any issues or any benefit to giving it a try? Dave
 

#407 Clive Gibbons

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Posted 10 September 2008 - 01:35 PM

Hello Daniel,

could you ever compare a 102mm Vixen Fluorite (fluorite crystal, like
the Takahashi FS, Zeiss APQ and some other scopes) to a 102mm Takahashi FS?
Some years ago I could observe with a 4" Vixen and was very pleased with
it`s performance. Concerning the 102/800mm TMB I can tell that Sven Wienstein
and me used one of them for our eyepiece and barlow comparisons:

http://www.svenwiens...arlow-test.html

It was unspectacular in a very positive way. No colour issues at all
and contrasty views. I would really like to compare it to a Takahashi TSA.

Regards, Karsten


I believe the Vixen and Tak FC series of flourite doublets both had the outer element flourite. The later FS series switched and put the flourite on the inner side of the doublet lens cell.


IIRC, the FC had the fluorite element internalized.
Same for the Vixen (which also left the FL element uncoated)
The FS had the fluorite as the outer element.
The later multicoating technology (which better protected the fluorite) allowed this change.
 

#408 KaStern

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Posted 10 September 2008 - 02:50 PM

Hello Clive,

IIRC, the FC had the fluorite element internalized.
Same for the Vixen (which also left the FL element uncoated)
The FS had the fluorite as the outer element.
The later multicoating technology (which better protected the fluorite) allowed this change.



I know for shure that the Vixen 102mm f/9 Fluorite has the crystal lens
at the inside. And it was not coated. I do not know about the Takahashi.

Clear skies, Karsten
 

#409 Daniel Mounsey

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Posted 10 September 2008 - 02:59 PM

I have a 90FL Vixen and 100FL badged as an Orion but built and marked as a Vixen. I have an FC 76 and an FC 100 (currently in transit) and these four scopes all seem to perform in a very similar fashion. Compared to 'modern' scopes in the the 3.5 to 4 aperture range, they are right up at in the top bracket but haven't done a recent test to do any ranking against the rest of my APO 'fleet.'

Tak also built flourite triplets, and I have an FCT 100 and a 150. My only other flourite triplet is a Zeiss 100/640 APQ. Those too also are supreb, the first and last being no doubt candidates along with the Vixen and the Tak doublets for further comparisons. Depends on whether time, location (Dan is out in Arnolt land and I live in Cheeseville) and other issues arise, but if Dan is game, I can try shipping him a scope or two from time to time to review. Dave


Dave,

In that case just send everything :lol: My goodness! and I thought I had a lot of scopes. :lol:
 

#410 JoeBftsplk

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Posted 10 September 2008 - 03:00 PM

IIRC, the FC had the fluorite element internalized.
Same for the Vixen (which also left the FL element uncoated)
The FS had the fluorite as the outer element.
The later multicoating technology (which better protected the fluorite) allowed this change.


Clive's right. FS has Fluorite element outside. An advance in hard coating made this possible. Fluorite-out made for a slightly superior design over the Fluorite-in FC...according to Takahashi. Read this the other day when I stumbled across my FS78 manual.
Bob
 

#411 Dave Novoselsky

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Posted 10 September 2008 - 03:17 PM

You are right, I am wrong. I suffer from Tak dyslexia. I KNOW better than this, the FC has the flourite element inside, the FS outside. Boy, did I get this backwards. Consider my wrist slapped on this one. Dave
 

#412 Dave Novoselsky

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Posted 10 September 2008 - 03:29 PM

Okay, to atone for my sin, here is the coating info on the Taks per Art at TNR. FCs, flourite element not coated until approx 1989, then it was coated, non-fl element always coated and later multi coated. FCT, the inner and outer elements were always coated, the inside fl element was never coated during the production run.

Mea culpa, mea maxima clupa. Dave
 

#413 Greg Morrison

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Posted 10 September 2008 - 05:14 PM

The FC series scopes were Steinheil doublets (steeper curves) and FS series are Fraunhofer doublets. I recall reading somewhere (can't remember where) that the Steinheil design is less sensitive to decentering. I've owned 2 FC series and 3 FS series Taks and I found them equally good.
 

#414 Dave Novoselsky

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Posted 10 September 2008 - 05:20 PM

I too have a hard time calling an FC better, or worse, than an FS. You can, and will, get some dispute on this either way at the various Tak groups. Dave
 

#415 Fomalhaut

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Posted 11 September 2008 - 02:05 AM

"...get some dispute on this either way at the various Tak groups. Dave"
-> various Tak groups? I know only the "uncensored Tak group" on Yahoo. Would you please name the other ones?
Chris
 

#416 Jeff Marsden

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Posted 11 September 2008 - 05:23 AM

The following appear on a Yahoo groups search. Some have a low membership number but they are there. Some of them are ‘specialist’ model groups but we all know from Cloudy Nights that a thread can deviate to something else! So I am sure that other telescope models can be brought into the debate other than the title of the Yahoo Group.

Takahashiusa
TakahashiOzGroup
Takahashi_FSQ_Refractor_Owners
USATAKAHASHIGROUP
Takahashi_TOA_Refractor_Owners
takahashi-europe

There might even be others out there, anyone?
Jeff
 

#417 Fomalhaut

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Posted 11 September 2008 - 06:41 AM

Thank you, Jeff
These groups seem to be tiny indeed
Chris
 

#418 mistyridge

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Posted 11 September 2008 - 06:38 PM

Daniel, thank you for a most interesting thread. I have been reading all the back and forth about various 4" to 4.5" scopes. I was wondering if anyone had done a comparison of some of the Stellarvue 102mm-115mm doublets or triplets? I think all the other major manufactuers have been covered.
 

#419 Daniel Mounsey

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Posted 11 September 2008 - 07:55 PM

I will attempt to do so when possible and add it to this thread.

Regards
 

#420 drshr

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Posted 12 September 2008 - 02:11 AM

Also the WO Megrez 102. Available on eBay and has to do better than the Megrez 110. :foreheadslap:
 

#421 Nick-Sydney

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Posted 13 September 2008 - 03:18 PM

Also the WO Megrez 102. Available on eBay and has to do better than the Megrez 110. :foreheadslap:


Would be good to see a comparison review of a decent M110ED and M102ED (or any of the similar 102ED scopes) with these scopes.

I'm sure there would be plenty of CN folks willing to do such reviews if vendors/manufacturers supplied them with test scopes.

I for one will stick my hand up and request that this happen. Surely if vendors stand behind the products they sell, it's in their interests to have their scopes tested and compared against others. It's certainly in OUR interests - and I think a lot of people would find it easier to part with their hard earned money if they could read an objective review comparing different scopes beforehand.

There really should be a shootout for the lower priced ED doublets in the 100-110mm range. Maybe another shootout for the 90mm scopes as well. Given that you generally can't test scopes out properly before you buy - I am amazed that these shootouts aren't more common.

More shootouts PLEASE!!!
 

#422 sabir

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Posted 13 September 2008 - 06:37 PM

Dear Dr. D

Thank you for that amazingly informative and fun to read review :D In fact I took a print out of it to relax and read it in bed ...just like your Planetary Ep's review. Nothing new about it,... this is what we have come to expect of you and you sure have spoiled us :)

I was wondering (rather dreaming,... its not like I'd be able to afford any of the scopes in your review any time soon :grin:) about the Pentax 105SDP and how it would stack up against the Tak TSA? I assume it would give it a very good run for the money?

Thank you again for the wonderful shoot out. You've just raised the bar! ;)

Sabir
 

#423 Arief

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Posted 13 September 2008 - 10:23 PM

Roland C. mentioned that the FC is (slightly) better corrected than the FS series due to the better mating element used in the FC series (KzF2): http://tech.groups.y...s/message/24167

I too have a hard time calling an FC better, or worse, than an FS. You can, and will, get some dispute on this either way at the various Tak groups. Dave


 


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